Abstract: Biological study of Silurus glaris Linnaeus that was transplanted in Yili River before was conducted, including of morpholo- gy measurement, age and growth relationship, reproduction and feeding habit. Growth equation of this fish species was calculated based on Von .Bertalanffy＇s method. The fish catches composed of individuals with body length of 16-121 cm, mainly in 40-70cm （60.36%）, individuals with body weight of 50-13400g, mainly in 500-20000g （56.7%） and individuals at 0^＋-8^＋ years old, mainly at 1^＋-3^＋ ages （55.85%）. The number of recruit populations was more than that of residual populations. The growth parameters were L∞=191.1cm, W∞=59 875g, -k=0.087, t0=0.038, tmax=34.5 and trt=12.7, respectively. Silurus glaris were able to achieve sex maturity and reproduce in June every year as it growed 4^＋ years old, 70cm and 3500g. The male fish had habits of construction net and protection egg, which were behaviors of typical carnivore. This fish species have advantages of fast growth, big body, strong adaptation and ex- tensive abilities, and easy to form populations when transplanted, therefore, Silurus glaris had become one of ecological fish species in Yili River.

Key words: Yili River, Silurus glads, Biology